Compare ACID and BASE consistency models in databases
Reported in Miro European engineering loops. Distributed data question bridging SQL transactions and NoSQL eventual consistency.
Interview scenario
Often asked in Miro loops at European offices (London, Berlin, Amsterdam, Paris, Stockholm, Dublin, and remote EU). Prepare a clear spoken answer plus key trade-offs.
Model answer
Try answering aloud first
Cover trade-offs, structure, and a concrete example before revealing the baseline response.
How to frame this at Miro: Connect your answer to measurable impact, clarity of thought, and trade-offs the team cares about. Below is a strong baseline response you can adapt with your own project examples.
ACID: Atomicity (all-or-nothing transactions), Consistency (valid state transitions), Isolation (concurrent txs behave serially), Durability (committed survives crash). Standard for relational OLTP—bank transfers require ACID.
BASE: Basically Available, Soft state, Eventual consistency—prioritizes availability and partition tolerance (AP in CAP). NoSQL systems like Cassandra, DynamoDB—replicas converge over time.
Choose ACID when correctness beats temporary unavailability—ledger, inventory. Choose BASE for high write throughput, global scale, and when business tolerates stale reads with version vectors or conflict resolution.
Modern nuance: many systems blend models—Spanner external consistency, PostgreSQL with read replicas lag, and saga patterns for cross-service ACID-like behavior.
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